What does "po304 pending" mean?
 

I had codes run again on 99' S500. It came back with po308 misfire and po304 pending. I replaced coil in cyl 8 and auto runs great. A very small glitch sporadically with no CEL.

Means the cylinder #4 has had some misfires, but not enough to set a check engine lamp.

Takes 200 consecutive misfires OR 1000 random misfires.

Either a coil or spark plug issue.

I pulled #4 coil and plug..covered with oil. Others look dry. What would be the cause? I have replace gaskets (kit) recently due to oil sepage but no oil was found in any plug cyl.

Most likely. OIL doesn't cause that problem, but even the slightest trace of moisture in the oil will.

Thanks DOC ,I guess my question was a little misleading. What could cause the oil around the plug? Also I was recently told to run a few cans of seafoam thru the brake booster hose and leave over nite. I must say it caused many to turn their heads as I appeared as a jet leaving its tail down the highway. I was also told to change the oil once the white smoke was gone. Could this cause moister in the chamber?

Then most likely a coil...try swapping to another cylinder.